5 May 1866 - the part of Arizona south of the 37° north latitude and west of 114° west longitude down to the Colorado River was given to Nevada by the United States.[1][2] All previous counties were discontinued and Nevada added the land to the southern parts of Lincoln and Nye counties.

Arizona did not accept this loss of land and twice patitioned the US Congress to reverse the law.

18 February 1871 - Arizona discontinued Pah-Ute County. It finally accepted the loss to Nevada and restored the remainder of this county to Mohave County Arizona.